Fragranced biodegradable film

ABSTRACT

A film formed from a biodegradable polymer matrix within which is contained at least one fragrance is provided. The ability to incorporate a fragrance into the polymer matrix is achieved in the present invention by controlling a variety of aspects of the film construction, including the nature of the fragrance, the nature of the biodegradable polymer, the manner in which the polymer matrix and fragrance are melt processed, etc. For example, the fragrance may be injected directly into the extruder and melt blended with the biodegradable polymer. In this manner, the costly and time-consuming steps of pre-encapsulation or pre-compounding of the fragrance into a masterbatch are not required. Furthermore, to obtain a balance between the ability of the fragrance to release the desired odor during use and likewise to minimize the premature exhaustion of the odor during melt processing, the fragrance is selected to have a boiling point (at atmospheric pressure) within a certain range, such as from about 125° C. to about 350° C.

BACKGROUND OF THE INVENTION

Fragrances have been added to packaging films and bags to counteractmalodor associated with certain applications (e.g., garbage disposal).U.S. Patent Application No. 2003/0204001 to Van Gelder, et al., forexample, describes a method for producing a polyethylene orpolypropylene film having a fragrance. The film is formed by adding aliquid fragrance to porous pellets of polyethylene or polypropylene,blending the mixture with an odor barrier (e.g., bis-fatty acid amide),and then extruding the blend into pellets to form a “masterbatch.” Themasterbatch may subsequently be mixed with a polyethylene orpolypropylene polymer at a ratio of 100:1 to 20:1 (ratio of polymer tomasterbatch) to form a film. Unfortunately, however, such techniques areoverly complex and costly in that they first require the formation of amasterbatch and they also require the use of an odor barrier to preventpremature evaporation of the fragrance.

As such, a need currently exists for an improved technique forincorporating a fragrance into a packaging film.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, a method forforming a fragranced film is disclosed that comprises supplying at leastone biodegradable polymer to an extruder; injecting at least one liquidfragrance into the extruder to form a blend comprising the biodegradablepolymer and the fragrance, wherein the liquid fragrance has a boilingpoint at atmospheric pressure of from about 125° C. to about 350° C.;and extruding the blend onto a surface to form a film.

Other features and aspects of the present invention are discussed ingreater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth more particularly in the remainder of the specification, whichmakes reference to the appended figures in which:

FIG. 1 is a partially broken away side view of an extruder that may beused in one embodiment of the present invention; and

FIG. 2 is a schematic illustration of one embodiment of a method forforming a film in accordance with the present invention.

Repeat use of references characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

Reference now will be made in detail to various embodiments of theinvention, one or more examples of which are set forth below. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations may be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment, may be used on another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

Generally speaking, the present invention is directed to a film formedfrom a biodegradable polymer matrix within which is contained at leastone fragrance. The ability to incorporate a fragrance into the polymermatrix is achieved in the present invention by controlling a variety ofaspects of the film construction, including the nature of the fragrance,the nature of the biodegradable polymer, the manner in which the polymermatrix and fragrance are melt processed, etc. For example, the fragrancemay be injected directly into the extruder and melt blended with thebiodegradable polymer. In this manner, the costly and time-consumingsteps of pre-encapsulation or pre-compounding of the fragrance into amasterbatch are not required. Furthermore, to obtain a balance betweenthe ability of the fragrance to release the desired odor during use andlikewise to minimize the premature exhaustion of the odor during meltprocessing, the fragrance is selected to have a boiling point (atatmospheric pressure) within a certain range, such as from about 125° C.to about 350° C.

In this regard, various embodiments of the present invention will now bedescribed in more detail below.

I. Film Components

A. Fragrance

Although any number of fragrances may generally be employed in the filmof the present invention to produce the desired odor, at least onefragrance is employed that is in the form of a liquid at ambienttemperature and pressure. The boiling point of such a liquid fragranceis normally selected within a certain range so that it is volatileenough to produce the desired odor, but not to such an extent that asignificant portion of the fragrance is released during melt processingof the film. In this regard, the fragrance typically has a boiling point(at atmospheric pressure) of from about 125° C. to about 350° C., insome embodiments, from about 150° C. to about 300° C., and in someembodiments, from about 175° C. to about 250° C. Some examples of suchfragrances may include, for instance, benzaldehyde, benzyl acetate,camphor, carvone, borneol, bornyl acetate, decyl alcohol, eucalyptol,linalool, hexyl acetate, iso-amyl acetate, thymol, carvacrol, limonene,menthol, iso-amyl alcohol, phenyl ethyl alcohol, alpha pinene, alphaterpineol, citronellol, alpha thujone, benzyl alcohol, beta gammahexenol, dimethyl benzyl carbinol, phenyl ethyl dimethyl carbinol,adoxal, allyl cyclohexane propionate, beta pinene, citral, citronellylacetate, citronellal nitrile, dihydro myrcenol, geraniol, geranylacetate, geranyl nitrile, hydroquinone dimethyl ether,hydroxycitronellal, linalyl acetate, phenyl acetaldehyde dimethylacetal, phenyl propyl alcohol, prenyl acetate, triplal,tetrahydrolinalool, verdox, cis-3-hexenyl acetate, etc., and mixturesthereof.

Of course, other fragrances may also be employed in the presentinvention as is well known in the art. For example, such fragrances mayinclude anethol, methyl heptine carbonate, ethyl aceto acetate, paracymene, nerol, decyl aldehyde, para cresol, methyl phenyl carbinylacetate, ionone alpha, ionone beta, undecylenic aldehyde, undecylaldehyde, 2,6-nonadienal, nonyl aldehyde, octyl aldehyde, phenylacetaldehyde, anisic aldehyde, benzyl acetone, ethyl-2-methyl butyrate,damascenone, damascone alpha, damascone beta, flor acetate, frutene,fructone, herbavert, isocyclo citral, methyl isobutenyl tetrahydropyran, isopropyl quinoline, 2,6-nonadien-1-ol,2-methoxy-3-(2-methylpropyl)-pyrazine, methyl octine carbonate,tridecene-2-nitrile, allyl amyl glycolate, cyclogalbanate, cyclal C,melonal, gamma nonalactone, cis 1,3-oxathiane-2-methyl-4-propyl, etc.,and mixtures thereof. Still other suitable fragrances are described inU.S. Pat. Nos. 4,145,184; 4,209,417; 4,515,705; and 4,152,272, all ofwhich are incorporated herein in their entirety by reference thereto forall purposes.

B. Biodegradable Polymer

The film of the present invention also contains one or morebiodegradable polymers that form a matrix within which the fragrance iscontained prior to disintegration of the film. The term “biodegradable”generally refers to a material that degrades from the action ofnaturally occurring microorganisms, such as bacteria, fungi, and algae;environmental heat; moisture; or other environmental factors, such asdetermined according to ASTM Test Method 5338.92. The biodegradablepolymer may be a naturally occurring polymer, synthetic polymer ormixtures thereof. Suitable naturally occurring biodegradable polymersmay include, for instance, polysaccharides (e.g., starch, celluloses,etc., as well as derivatives thereof), proteins (e.g., casein, gelatin,etc.), polyesters (e.g., polyhydroxyalkanoates (PHA)). Likewise,suitable synthetic biodegradable polymers may include, for instance,aliphatic polyesters, such as polycaprolactone, polyesteramides,modified polyethylene terephthalate, polylactic acid (PLA) and itscopolymers, terpolymers based on polylactic acid, polyglycolic acid,polyalkylene carbonates (such as polyethylene carbonate),poly-3-hydroxybutyrate (PHB), poly-3-hydroxyvalerate (PHV),poly-3-hydroxybutyrate-co-4-hydroybutyrate,poly-3-hydroxybutyrate-co-3-hydroxyvalerate copolymers (PHBV),poly-3-hydroxybutyrate-co-3-hydroxyhexanoate,poly-3-hydroxybutyrate-co-3-hydroxyoctanoate,poly-3-hydroxybutyrate-co-3-hydroxydecanoate,poly-3-hydroxybutyrate-co-3-hydroxyoctadecanoate, and succinate-basedaliphatic polymers (e.g., polybutylene succinate, polybutylene succinateadipate, polyethylene succinate, etc.); aromatic polyesters and modifiedaromatic polyesters; aliphatic-aromatic copolyesters; and so forth.

In one particular embodiment, an aliphatic-aromatic copolyester isemployed that is synthesized using any known technique, such as throughthe condensation polymerization of a polyol in conjunction withaliphatic and aromatic dicarboxylic acids or anhydrides thereof. Thepolyols may be substituted or unsubstituted, linear or branched, polyolsselected from polyols containing 2 to about 12 carbon atoms andpolyalkylene ether glycols containing 2 to 8 carbon atoms. Examples ofpolyols that may be used include, but are not limited to, ethyleneglycol, diethylene glycol, propylene glycol, 1,2-propanediol,1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,2-butanediol,1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol,1,6-hexanediol, polyethylene glycol, diethylene glycol,2,2,4-trimethyl-1,6-hexanediol, thiodiethanol,1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol,2,2,4,4-tetramethyl-1,3-cyclobutanediol, cyclopentanediol, triethyleneglycol, and tetraethylene glycol. Preferred polyols include1,4-butanediol; 1,3-propanediol; ethylene glycol; 1,6-hexanediol;diethylene glycol; and 1,4-cyclohexanedimethanol.

Representative aliphatic dicarboxylic acids that may be used includesubstituted or unsubstituted, linear or branched, non-aromaticdicarboxylic acids selected from aliphatic dicarboxylic acids containing2 to about 10 carbon atoms, and derivatives thereof. Non-limitingexamples of aliphatic dicarboxylic acids include malonic, malic,succinic, oxalic, glutaric, adipic, pimelic, azelaic, sebacic, fumaric,2,2-dimethyl glutaric, suberic, 1,3-cyclopentanedicarboxylic,1,4-cyclohexanedicarboxylic, 1,3-cyclohexanedicarboxylic, diglycolic,itaconic, maleic, and 2,5-norbornanedicarboxylic. Representativearomatic dicarboxylic acids that may be used include substituted andunsubstituted, linear or branched, aromatic dicarboxylic acids selectedfrom aromatic dicarboxylic acids containing 8 or more carbon atoms, andderivatives thereof. Non-limiting examples of aromatic dicarboxylicacids include terephthalic acid, dimethyl terephthalate, isophthalicacid, dimethyl isophthalate, 2,6-napthalene dicarboxylic acid,dimethyl-2,6-naphthalate, 2,7-naphthalenedicarboxylic acid,dimethyl-2,7-naphthalate, 3,4′-diphenyl ether dicarboxylic acid,dimethyl-3,4′diphenyl ether dicarboxylate, 4,4′-diphenyl etherdicarboxylic acid, dimethyl-4,4′-diphenyl ether dicarboxylate,3,4′-diphenyl sulfide dicarboxylic acid, dimethyl-3,4′-diphenyl sulfidedicarboxylate, 4,4′-diphenyl sulfide dicarboxylic acid,dimethyl-4,4′-diphenyl sulfide dicarboxylate, 3,4′-diphenyl sulfonedicarboxylic acid, dimethyl-3,4′-diphenyl sulfone dicarboxylate,4,4′-diphenyl sulfone dicarboxylic acid, dimethyl-4,4′-diphenyl sulfonedicarboxylate, 3,4′-benzophenonedicarboxylic acid,dimethyl-3,4′-benzophenonedicarboxylate, 4,4′-benzophenonedicarboxylicacid, dimethyl-4,4′-benzophenonedicarboxylate, 1,4-naphthalenedicarboxylic acid, dimethyl-1,4-naphthalate, 4,4′-methylene bis(benzoicacid), dimethyl-4,4′-methylenebis(benzoate), etc., and mixtures thereof.

If desired, a diisocyanate chain extender may be reacted with thecopolyester to increase its molecular weight. Representativediisocyanates may include toluene 2,4-diisocyanate, toluene2,6-diisocyanate, 2,4′-diphenylmethane diisocyanate,naphthylene-1,5-diisocyanate, xylylene diisocyanate, hexamethylenediisocyanate (“HMDI”), isophorone diisocyanate andmethylenebis(2-isocyanatocyclohexane). Trifunctional isocyanatecompounds may also be employed that contain isocyanurate and/or biureagroups with a functionality of not less than three, or to replace thediisocyanate compounds partially by tri-or polyisocyanates. Thepreferred diisocyanate is hexamethylene diisocyanate. The amount of thechain extender employed is typically from about 0.3 to about 3.5 wt. %,in some embodiments, from about 0.5 to about 2.5 wt. % based on thetotal weight percent of the polymer.

The copolyesters may either be a linear polymer or a long-chain branchedpolymer. Long-chain branched polymers are generally prepared by using alow molecular weight branching agent, such as a polyol, polycarboxylicacid, hydroxy acid, and so forth. Representative low molecular weightpolyols that may be employed as branching agents include glycerol,trimethylolpropane, trimethylolethane, polyethertriols,1,2,4-butanetriol, pentaerythritol, 1,2,6-hexanetriol, sorbitol,1,1,4,4,-tetrakis(hydroxymethyl)cyclohexane,tris(2-hydroxyethyl)isocyanurate, and dipentaerythritol. Representativehigher molecular weight polyols (molecular weight of 400 to 3000) thatmay be used as branching agents include triols derived by condensingalkylene oxides having 2 to 3 carbons, such as ethylene oxide andpropylene oxide with polyol initiators. Representative polycarboxylicacids that may be used as branching agents include hemimellitic acid,trimellitic (1,2,4-benzenetricarboxylic) acid and anhydride, trimesic(1,3,5-benzenetricarboxylic) acid, pyromellitic acid and anhydride,benzenetetracarboxylic acid, benzophenone tetracarboxylic acid,1,1,2,2-ethane-tetracarboxylic acid, 1,1,2-ethanetricarboxylic acid,1,3,5-pentanetricarboxylic acid, and 1,2,3,4-cyclopentanetetracarboxylicacid. Representative hydroxy acids that may be used as branching agentsinclude malic acid, citric acid, tartaric acid, 3-hydroxyglutaric acid,mucic acid, trihydroxyglutaric acid, 4-carboxyphthalic anhydride,hydroxyisophthalic acid, and 4-(beta-hydroxyethyl)phthalic acid. Suchhydroxy acids contain a combination of 3 or more hydroxyl and carboxylgroups. Especially preferred branching agents include trimellitic acid,trimesic acid, pentaerythritol, trimethylol propane and1,2,4-butanetriol.

The aromatic dicarboxylic acid monomer constituent may be present in thecopolyester in an amount of from about 10 mole % to about 40 mole %, insome embodiments from about 15 mole % to about 35 mole %, and in someembodiments, from about 15 mole % to about 30 mole %. The aliphaticdicarboxylic acid monomer constituent may likewise be present in thecopolyester in an amount of from about 15 mole % to about 45 mole %, insome embodiments from about 20 mole % to about 40 mole %, and in someembodiments, from about 25 mole % to about 35 mole %. The polyol monomerconstituent may also be present in the aliphatic-aromatic copolyester inan amount of from about 30 mole % to about 65 mole %, in someembodiments from about 40 mole % to about 50 mole %, and in someembodiments, from about 45 mole % to about 55 mole %.

In one particular embodiment, for example, the aliphatic-aromaticcopolyester may comprise the following structure:

wherein,

m is an integer from 2 to 10, in some embodiments from 2 to 4, and inone embodiment, 4;

n is an integer from 0 to 18, in some embodiments from 2 to 4, and inone embodiment, 4;

p is an integer from 2 to 10, in some embodiments from 2 to 4, and inone embodiment, 4;

x is an integer greater than 1; and

y is an integer greater than 1. One example of such a copolyester ispolybutylene adipate terephthalate, which is commercially availableunder the designation ECOFLEX® F BX 7011 from BASF Corp. Another exampleof a suitable copolyester containing an aromatic terephthalic acidmonomer constituent is available under the designation ENPOL™ 8060M fromIRE Chemicals (South Korea). Other suitable aliphatic-aromaticcopolyesters may be described in U.S. Pat. Nos. 5,292,783; 5,446,079;5,559,171; 5,580,911; 5,599,858; 5,817,721; 5,900,322; and 6,258,924,which are incorporated herein in their entirety by reference thereto forall purposes.

Starches may also be employed in the film that are biodegradable. Nativestarches may be employed, such as those that obtained from corn, waxycorn, wheat, sorghum, rice, and waxy rice; tubers, such as potatoes;roots, such as tapioca (i.e., cassava and manioc), sweet potato, andarrowroot; and the pith of the sago palm. The starches may also bechemically modified (e.g., esterification, etherification, oxidation,enzymatic hydrolysis, etc.). Starch ethers and/or esters may beparticularly desirable, such as hydroxyalkyl starches, carboxymethylstarches, etc. The hydroxyalkyl group of hydroxylalkyl starches maycontain, for instance, 2 to 10 carbon atoms, in some embodiments from 2to 6 carbon atoms, and in some embodiments, from 2 to 4 carbon atoms.Representative hydroxyalkyl starches such as hydroxyethyl starch,hydroxypropyl starch, hydroxybutyl starch, and derivatives thereof.Starch esters, for instance, may be prepared using a wide variety ofanhydrides (e.g., acetic, propionic, butyric, and so forth), organicacids, acid chlorides, or other esterification reagents. The degree ofesterification may vary as desired, such as from 1 to 3 ester groups perglucosidic unit of the starch.

Through selective control over the nature of the biodegradable polymer(e.g., melt flow index) and the relative amounts of the biodegradablepolymer and fragrance, the biodegradable polymer may achieve a meltviscosity that is compatible with the fragrance, which further helpsminimize phase separation during formation of the film. For example, themelt flow index of the biodegradable polymer may range from about 0.1 toabout 10 grams per 10 minutes, in some embodiments from about 0.5 toabout 8 grams per 10 minutes, and in some embodiments, from about 1 toabout 5 grams per 10 minutes. The melt flow index is the weight of apolymer (in grams) that may be forced through an extrusion rheometerorifice (0.0825-inch diameter) when subjected to a load of 2160 grams in10 minutes at a certain temperature (e.g., 190° C.), measured inaccordance with ASTM Test Method D1238-E.

The molecular weight of the polymer may be selected to achieve thedesired viscosity. Synthetic biodegradable polyesters, for example,typically have a number average molecular weight (“M_(n)”) ranging fromabout 40,000 to about 120,000 grams per mole, in some embodiments fromabout 50,000 to about 100,000 grams per mole, and in some embodiments,from about 60,000 to about 85,000 grams per mole. Likewise, the polymermay also have a weight average molecular weight (“M_(w)”) ranging fromabout 70,000 to about 360,000 grams per mole, in some embodiments fromabout 80,000 to about 250,000 grams per mole, and in some embodiments,from about 100,000 to about 200,000 grams per mole. Starches, on theother hand, may have a higher molecular weight, such as a number averagemolecular weight (“M_(n)”) of from about 50,000 to about 1,000,000 gramsper mole, in some embodiments from about 75,000 to about 800,000 gramsper mole, and in some embodiments, from about 100,000 to about 600,000grams per mole, as well as a weight average molecular weight (“M_(w)”)ranging from about 5,000,000 to about 25,000,000 grams per mole, in someembodiments from about 5,500,000 to about 15,000,000 grams per mole, andin some embodiments, from about 6,000,000 to about 12,000,000 grams permole.

The biodegradable polymer also typically has a melting point of fromabout 40° C. to about 200° C., in some embodiments from about 80° C. toabout 180° C., and in some embodiments, from about 100° C. to about 160°C. The glass transition temperature (“T_(g)”) of the biodegradablepolymer is also normally low to impart flexibility and processability ofthe polymers. For example, the T_(g) may be about 25° C. or less, insome embodiments about 0° C. or less, and in some embodiments, about−10° C. or less. The melting temperature and glass transitiontemperature may be determined using differential scanning calorimetry(“DSC”) in accordance with ASTM D-3417.

The relative amount of the biodegradable polymers and fragrancesemployed in the film may also be selected to help further minimize phaseseparation. For example, the weight ratio of biodegradable polymers tofragrances is typically from about 1 to about 500, in some embodimentsfrom about 10 to about 200, and in some embodiments, from about 20 toabout 80. Fragrances, for example, may constitute from about 0.1 wt. %to about 15 wt. %, in some embodiments from about 0.5 wt. % to about 10wt. %, and in some embodiments, from about 1 wt. % to about 5 wt. % ofthe film. Biodegradable polymers may constitute from about 40 wt. % toabout 99.9 wt. %, in some embodiments from about 50 wt. % to about 99.5wt. %, and in some embodiments, from about 60 wt. % to about 99 wt. % ofthe film.

C. Other Components

Other components may also be incorporated into the film as is known inthe art. For example, a plasticizer may be employed in the film of thepresent invention to help render certain components melt processible.Suitable plasticizers may include, for instance, polyhydric alcoholplasticizers, such as sugars (e.g., glucose, sucrose, fructose,raffinose, maltodextrose, galactose, xylose, maltose, lactose, mannose,and erythrose), sugar alcohols (e.g., erythritol, xylitol, malitol,mannitol, and sorbitol), polyols (e.g., ethylene glycol, glycerol,propylene glycol, dipropylene glycol, butylene glycol, and hexanetriol), etc. Also suitable are hydrogen bond forming organic compoundswhich do not have hydroxyl group, including urea and urea derivatives;anhydrides of sugar alcohols such as sorbitan; animal proteins such asgelatin; vegetable proteins such as sunflower protein, soybean proteins,cotton seed proteins; and mixtures thereof. Other suitable plasticizersmay include phthalate esters, dimethyl and diethylsuccinate and relatedesters, glycerol triacetate, glycerol mono and diacetates, glycerolmono, di, and tripropionates, butanoates, stearates, lactic acid esters,citric acid esters, adipic acid esters, stearic acid esters, oleic acidesters, and other acid esters. Aliphatic acids may also be used, such ascopolymers of ethylene and acrylic acid, polyethylene grafted withmaleic acid, polybutadiene-co-acrylic acid, polybutadiene-co-maleicacid, polypropylene-co-acrylic acid, polypropylene-co-maleic acid, andother hydrocarbon based acids. A low molecular weight plasticizer ispreferred, such as less than about 20,000 g/mol, preferably less thanabout 5,000 g/mol and more preferably less than about 1,000 g/mol. Whenemployed, the film may contain from about 1 wt. % to about 40 wt. %, insome embodiments from about 2 wt. % to about 30 wt. %, and in someembodiments, from about 5 wt. % to about 25 wt. % of plasticizers.

Water-soluble polymers may also be employed in the film, such as thosecontaining a repeating unit having a functional hydroxyl group, such asvinyl alcohol homopolymers (e.g., “PVOH”), vinyl alcohol copolymers(e.g., ethylene vinyl alcohol copolymers, methyl methacrylate vinylalcohol copolymers, etc.), etc. Vinyl alcohol polymers, for instance,have at least two or more vinyl alcohol units in the molecule and may bea homopolymer of vinyl alcohol, or a copolymer containing other monomerunits. Vinyl alcohol homopolymers may be obtained by hydrolysis of avinyl ester polymer, such as vinyl formate, vinyl acetate, vinylpropionate, etc. Vinyl alcohol copolymers may be obtained by hydrolysisof a copolymer of a vinyl ester with an olefin having 2 to 30 carbonatoms, such as ethylene, propylene, 1-butene, etc.; an unsaturatedcarboxylic acid having 3 to 30 carbon atoms, such as acrylic acid,methacrylic acid, crotonic acid, maleic acid, fumaric acid, etc., or anester, salt, anhydride or amide thereof; an unsaturated nitrile having 3to 30 carbon atoms, such as acrylonitrile, methacrylonitrile, etc.; avinyl ether having 3 to 30 carbon atoms, such as methyl vinyl ether,ethyl vinyl ether, etc.; and so forth. The degree of hydrolysis of suchpolymers may be selected to optimize solubility, etc., of the polymer.For example, the degree of hydrolysis may be from about 60 mole % toabout 95 mole %, in some embodiments from about 80 mole % to about 90mole %, and in some embodiments, from about 85 mole % to about 89 mole%. Examples of suitable partially hydrolyzed polyvinyl alcohol polymersare available under the designation CELVOL™ 203, 205, 502, 504, 508,513, 518, 523, 530, or 540 from Celanese Corp. Other suitable partiallyhydrolyzed polyvinyl alcohol polymers are available under thedesignation ELVANOL™ 50-14, 50-26, 50-42, 51-03, 51-04, 51-05, 51-08,and 52-22 from DuPont.

Other water-soluble polymers may also be employed. For example,water-soluble polymers may also be formed from monomers such as vinylpyrrolidone, hydroxyethyl acrylate or methacrylate (e.g., 2-hydroxyethylmethacrylate), hydroxypropyl acrylate or methacrylate, acrylic ormethacrylic acid, acrylic or methacrylic esters or vinyl pyridine,acrylamide, vinyl acetate, ethylene oxide, derivatives thereof, and soforth. Mixes or blends of two or more water soluble polymers may also beused in this invention to provide balanced water-solubility, meltprocessability, mechanical properties and or physical properties.Example of the blends of water soluble polymers include blends ofpolyvinyl alcohol and polyethylene oxide as disclosed in U.S. Pat. No.6,958,371 to Wang, et al. Other examples of suitable monomers aredescribed in U.S. Pat. No. 4,499,154 to James, et al., which isincorporated herein in its entirety by reference thereto for allpurposes. When employed, the film may contain from about 1 wt. % toabout 40 wt. %, in some embodiments from about 2 wt. % to about 30 wt.%, and in some embodiments, from about 5 wt. % to about 25 wt. % ofwater-soluble polymers.

In addition to the components noted above, other additives may also beincorporated into the film of the present invention, such as slipadditives (e.g., fatty acid salts, fatty acid amides, etc.),compatibilizers (e.g., functionalized polyolefins), dispersion aids,melt stabilizers, processing stabilizers, heat stabilizers, lightstabilizers, antioxidants, heat aging stabilizers, whitening agents,antiblocking agents, bonding agents, lubricants, fillers, etc.Dispersion aids, for instance, may also be employed to help create auniform dispersion of the biodegradable polymer and fragrance and retardor prevent separation into constituent phases. When employed, thedispersion aid(s) typically constitute from about 0.01 wt. % to about 15wt. %, in some embodiments from about 0.1 wt. % to about 10 wt. %, andin some embodiments, from about 0.5 wt. % to about 5 wt. % of the film.Although any dispersion aid may generally be employed in the presentinvention, surfactants having a certain hydrophilic/lipophilic balance(“HLB”) may improve the long-term stability of the composition. The HLBindex is well known in the art and is a scale that measures the balancebetween the hydrophilic and lipophilic solution tendencies of acompound. The HLB scale ranges from 1 to approximately 50, with thelower numbers representing highly lipophilic tendencies and the highernumbers representing highly hydrophilic tendencies. In some embodimentsof the present invention, the HLB value of the surfactants is from about1 to about 20, in some embodiments from about 1 to about 15 and in someembodiments, from about 2 to about 10. If desired, two or moresurfactants may be employed that have HLB values either below or abovethe desired value, but together have an average HLB value within thedesired range.

One particularly suitable class of surfactants for use in the presentinvention are nonionic surfactants, which typically have a hydrophobicbase (e.g., long chain alkyl group or an alkylated aryl group) and ahydrophilic chain (e.g., chain containing ethoxy and/or propoxymoieties). For instance, some suitable nonionic surfactants that may beused include, but are not limited to, ethoxylated alkylphenols,ethoxylated and propoxylated fatty alcohols, polyethylene glycol ethersof methyl glucose, polyethylene glycol ethers of sorbitol, ethyleneoxide-propylene oxide block copolymers, ethoxylated esters of fatty(C₈-C₁₈) acids, condensation products of ethylene oxide with long chainamines or amides, condensation products of ethylene oxide with alcohols,fatty acid esters, monoglyceride or diglycerides of long chain alcohols,and mixtures thereof. In one particular embodiment, the nonionicsurfactant may be a fatty acid ester, such as a sucrose fatty acidester, glycerol fatty acid ester, propylene glycol fatty acid ester,sorbitan fatty acid ester, pentaerythritol fatty acid ester, sorbitolfatty acid ester, and so forth. The fatty acid used to form such estersmay be saturated or unsaturated, substituted or unsubstituted, and maycontain from 6 to 22 carbon atoms, in some embodiments from 8 to 18carbon atoms, and in some embodiments, from 12 to 14 carbon atoms. Inone particular embodiment, mono- and di-glycerides of fatty acids may beemployed in the present invention.

Fillers may also be employed in the present invention. Fillers areparticulates or other forms of material that may be added to the filmpolymer extrusion blend and that will not chemically interfere with theextruded film, but which may be uniformly dispersed throughout the film.Fillers may serve a variety of purposes, including enhancing filmopacity and/or breathability (i.e., vapor-permeable and substantiallyliquid-impermeable). For instance, filled films may be made breathableby stretching, which causes the polymer to break away from the fillerand create microporous passageways. Breathable microporous elastic filmsare described, for example, in U.S. Pat. Nos. 5,997,981; 6,015,764; and6,111,163 to McCormack, et al.; U.S. Pat. No. 5,932,497 to Morman, etal.; U.S. Pat. No. 6,461,457 to Taylor, et al., which are incorporatedherein in their entirety by reference thereto for all purposes. Further,hindered phenols are commonly used as an antioxidant in the productionof films. Some suitable hindered phenols include those available fromCiba Specialty Chemicals under the trade name “Irganox®”, such asIrganox® 1076, 1010, or E 201. Moreover, bonding agents may also beadded to the film to facilitate bonding of the film to additionalmaterials (e.g., nonwoven webs). Examples of such bonding agents includehydrogenated hydrocarbon resins. Other suitable bonding agents aredescribed in U.S. Pat. No. 4,789,699 to Kieffer et al. and U.S. Pat. No.5,695,868 to McCormack, which are incorporated herein in their entiretyby reference thereto for all purposes.

II. Film Construction

As indicated above, the fragrance is typically injected in a liquid formdirectly into the extruder and melt blended with the biodegradablepolymer. In this manner, the costly and time-consuming steps ofpre-encapsulation or pre-compounding of the fragrance are not required.Referring to FIG. 1, for example, one embodiment of an extruder 80 thatmay be employed for this purpose is illustrated. As shown, the extruder80 contains a housing or barrel 114 and a screw 120 (e.g., barrierscrew) rotatably driven on one end by a suitable drive 124 (typicallyincluding a motor and gearbox). If desired, a twin-screw extruder may beemployed that contains two separate screws. The extruder 80 generallycontains three sections: the feed section 132, the melt section 134, andthe mixing section 136. The feed section 132 is the input portion of thebarrel 114 where the plastic material is added. The melt section 134 isthe phase change section in which the plastic material is changed from asolid to a liquid. The mixing section 136 is adjacent the output end ofthe barrel 114 and is the portion in which the liquid plastic materialis completely mixed. While there is no precisely defined delineation ofthese sections when the extruder is manufactured, it is well within theordinary skill of those in this art to reliably identify the meltsection 134 of the extruder barrel 114 in which phase change from solidto liquid is occurring.

A hopper 40 is also located adjacent to the drive 124 for supplying thebiodegradable polymer and/or other materials through an opening 142 inthe barrel 114 to the feed section 132. Opposite the drive 124 is theoutput end 144 of the extruder 80, where extruded plastic is output forfurther processing to form a film, which will be described in moredetail below. A liquid fragrance supply station 150 is also provided onthe extruder barrel 114 that includes at least one hopper 154, which isattached to a pump 160 to selectively provide the liquid fragrancethrough an opening 162 to the melt section 134. In this manner, thefragrance may be mixed with the biodegradable polymer in a consistentand uniform manner. Of course, in addition to or in lieu of supplyingthe liquid fragrance to the melt section 134, it should also beunderstood that the liquid fragrance may be supplied to other sectionsof the extruder, such as the feed section 132 and/or the mixing section136.

The pump 160 may be a high pressure pump (e.g., positive displacementpump) with an injection valve so as to provide a steady selected amountof fragrance to the barrel 114. If desired, a programmable logiccontroller 170 may also be employed to connect the drive 124 to the pump160 so that it provides a selected volume of fragrance based on thedrive rate of the screw 120. That is, the controller 170 may control therate of rotation of the drive screw 120 and the pump 160 to inject thefragrance at a rate based on the screw rotation rate. Accordingly, ifthe rotation rate of the screw 120 is increased to drive greater amountsof plastic through the barrel 114 in a given unit of time, the pumpingrate of the pump 160 may be similarly increased to pump proportionatelygreater amounts of fragrance into the barrel 114.

Once injected into the extruder 80, the fragrance and biodegradablepolymer may be blended under high shear/pressure and heat to ensuresufficient mixing. For example, melt blending may occur at a temperatureof from about 75° C. to about 350° C., in some embodiments, from about100° C. to about 300° C., and in some embodiments, from about 150° C. toabout 250° C. Likewise, the apparent shear rate during melt blending mayrange from about 100 seconds⁻¹ to about 10,000 seconds⁻¹, in someembodiments from about 500 seconds⁻¹ to about 5000 seconds⁻¹, and insome embodiments, from about 800 seconds⁻¹ to about 1200 seconds⁻¹. Theapparent shear rate is equal to 4 Q/πR³, where Q is the volumetric flowrate (“m³/s”) of the polymer melt and R is the radius (“m”) of thecapillary (e.g., extruder die) through which the melted polymer flows.

Any known technique may be used to form a film from the blendedmaterial, including blowing, casting, flat die extruding, etc. In oneparticular embodiment, the film may be formed by a blown process inwhich a gas (e.g., air) is used to expand a bubble of the extrudedpolymer blend through an annular die. The bubble is then collapsed andcollected in flat film form. Processes for producing blown films aredescribed, for instance, in U.S. Pat. No. 3,354,506 to Raley; U.S. Pat.No. 3,650,649 to Schippers; and U.S. Pat. No. 3,801,429 to Schrenk etal., as well as U.S. Patent Application Publication Nos. 2005/0245162 toMcCormack, et al. and 2003/0068951 to Boggs, et al., all of which areincorporated herein in their entirety by reference thereto for allpurposes. In yet another embodiment, however, the film is formed using acasting technique.

Referring to FIG. 2, for instance, one embodiment of a method forforming a cast film is shown. In this embodiment, the raw materials (notshown) are supplied to the extruder 80 in the manner described above andshown in FIG. 1, and then cast onto a casting roll 90 to form asingle-layered precursor film 10 a. If a multilayered film is to beproduced, the multiple layers are co-extruded together onto the castingroll 90. The casting roll 90 may optionally be provided with embossingelements to impart a pattern to the film. Typically, the casting roll 90is kept at temperature sufficient to solidify and quench the sheet 10 aas it is formed, such as from about 20 to 60° C. If desired, a vacuumbox may be positioned adjacent to the casting roll 90 to help keep theprecursor film 10 a close to the surface of the roll 90. Additionally,air knives or electrostatic pinners may help force the precursor film 10a against the surface of the casting roll 90 as it moves around aspinning roll. An air knife is a device known in the art that focuses astream of air at a very high flow rate to pin the edges of the film.

Once cast, the film 10 a may then be optionally oriented in one or moredirections to further improve film uniformity and reduce thickness.Orientation may also form micropores in a film containing a filler, thusproviding breathability to the film. For example, the film may beimmediately reheated to a temperature below the melting point of one ormore polymers in the film, but high enough to enable the composition tobe drawn or stretched. In the case of sequential orientation, the“softened” film is drawn by rolls rotating at different speeds ofrotation such that the sheet is stretched to the desired draw ratio inthe longitudinal direction (machine direction). This “uniaxially”oriented film may then be laminated to a fibrous web. In addition, theuniaxially oriented film may also be oriented in the cross-machinedirection to form a “biaxially oriented” film. For example, the film maybe clamped at its lateral edges by chain clips and conveyed into atenter oven. In the tenter oven, the film may be reheated and drawn inthe cross-machine direction to the desired draw ratio by chain clipsdiverged in their forward travel.

Referring again to FIG. 2, for instance, one method for forming auniaxially oriented film is shown. As illustrated, the precursor film 10a is directed to a film-orientation unit 100 or machine directionorienter (“MDO”), such as commercially available from Marshall andWillams, Co. of Providence, R.I. The MDO has a plurality of stretchingrolls (such as from 5 to 8) which progressively stretch and thin thefilm in the machine direction, which is the direction of travel of thefilm through the process as shown in FIG. 2. While the MDO 100 isillustrated with eight rolls, it should be understood that the number ofrolls may be higher or lower, depending on the level of stretch that isdesired and the degrees of stretching between each roll. The film may bestretched in either single or multiple discrete stretching operations.It should be noted that some of the rolls in an MDO apparatus may not beoperating at progressively higher speeds. If desired, some of the rollsof the MDO 100 may act as preheat rolls. If present, these first fewrolls heat the film 10 a above room temperature (e.g., to 125° F.). Theprogressively faster speeds of adjacent rolls in the MDO act to stretchthe film 10 a. The rate at which the stretch rolls rotate determines theamount of stretch in the film and final film weight.

The resulting film 10 b may then be wound and stored on a take-up roll60. While not shown here, various additional potential processing and/orfinishing steps known in the art, such as slitting, treating,aperturing, printing graphics, or lamination of the film with otherlayers (e.g., nonwoven web materials), may be performed withoutdeparting from the spirit and scope of the invention.

The thickness of the resulting biodegradable film may generally varydepending upon the desired use. Typically, however, the film has athickness of about 50 micrometers or less, in some embodiments fromabout 1 to about 100 micrometers, in some embodiments from about 5 toabout 75 micrometers, and in some embodiments, from about 10 to about 60micrometers. Despite having such a small thickness, the film of thepresent invention is nevertheless able to retain good dry mechanicalproperties during use. One parameter that is indicative of the relativedry strength of the film is the ultimate tensile strength, which isequal to the peak stress obtained in a stress-strain curve. Desirably,the film of the present invention exhibits an ultimate tensile strengthin the machine direction (“MD”) of from about 1 to about 50 Megapascals(MPa), in some embodiments from about 5 to about 40 MPa, and in someembodiments, from about 10 to about 30 MPa, and an ultimate tensilestrength in the cross-machine direction (“CD”) of from about 1 to about50 Megapascals (MPa), in some embodiments from about 5 to about 40 MPa,and in some embodiments, from about 10 to about 30 MPa. Althoughpossessing good strength, it is also desirable that the film is not toostiff. One parameter that is indicative of the relative stiffness of thefilm (when dry) is Young's modulus of elasticity, which is equal to theratio of the tensile stress to the tensile strain and is determined fromthe slope of a stress-strain curve. For example, the film typicallyexhibits a Young's modulus in the machine direction (“MD”) of from about100 to about 1500 Megapascals (“MPa”), in some embodiments from about200 to about 1000 MPa, and in some embodiments, from about 300 to about900 MPa, and a Young's modulus in the cross-machine direction (“CD”) offrom about 75 to about 1200 Megapascals (“MPa”), in some embodimentsfrom about 175 to about 900 MPa, and in some embodiments, from about 250to about 850 MPa.

The film of the present invention may be mono- or multi-layered.Multilayer films may be prepared by co-extrusion of the layers,extrusion coating, or by any conventional layering process. Suchmultilayer films normally contain at least one base layer and at leastone skin layer, but may contain any number of layers desired. Forexample, the multilayer film may be formed from a base layer and one ormore skin layers, wherein the base layer is formed from a blend of thebiodegradable polymer and fragrance. In most embodiments, the skinlayer(s) are also formed from the blend as described above. It should beunderstood, however, that other polymers may also be employed in theskin layer(s).

III. Articles

The biodegradable film of the present invention is generally intendedfor use in the packaging of items, such as food products, medicalproducts, garments, garbage, absorbent articles (e.g., diapers), tissueproducts, and so forth. Of course, the biodegradable film of the presentinvention is versatile and may also be used with other types of articlesof manufacture. For example, the film may be used in an absorbentarticle. An “absorbent article” generally refers to any article capableof absorbing water or other fluids. Examples of some absorbent articlesinclude, but are not limited to, personal care absorbent articles, suchas diapers, training pants, absorbent underpants, incontinence articles,feminine hygiene products (e.g., sanitary napkins, pantiliners, etc.),swim wear, baby wipes, and so forth; medical absorbent articles, such asgarments, fenestration materials, underpads, bedpads, bandages,absorbent drapes, and medical wipes; food service wipers; clothingarticles; and so forth. Several examples of such absorbent articles aredescribed in U.S. Pat. No. 5,649,916 to DiPalma, et al.; U.S. Pat. No.6,110,158 to Kielpikowski; U.S. Pat. No. 6,663,611 to Blaney, et al.,which are incorporated herein in their entirety by reference thereto forall purposes. Still other suitable articles are described in U.S. PatentApplication Publication No. 2004/0060112 A1 to Fell et al., as well asU.S. Pat. No. 4,886,512 to Damico et al.; U.S. Pat. No. 5,558,659 toSherrod et al.; U.S. Pat. No. 6,888,044 to Fell et al.; and U.S. Pat.No. 6,511,465 to Freiburger et al., all of which are incorporated hereinin their entirety by reference thereto for all purposes. When employedin the absorbent article, the film of the present invention may form thebacksheet, topsheet, release liner, waist band, side panel, and/or anyother material or component of the absorbent article as is well known inthe art.

The present invention may be better understood with reference to thefollowing example.

Test Methods

Tensile Properties:

The strip tensile strength values were determined in substantialaccordance with ASTM Standard D638-99. A constant-rate-of-extension typeof tensile tester was employed. The tensile testing system was a Sintech1/D tensile tester, which is available from Sintech Corp. of Cary, N.C.The tensile tester was equipped with TESTWORKS 4.08B software from MTSCorporation to support the testing. An appropriate load cell wasselected so that the tested value fell within the range of 10-90% of thefull scale load. The film samples were initially cut into dog-boneshapes with a center width of 3.0 mm before testing. The samples wereheld between grips having a front and back face measuring 25.4millimeters×76 millimeters. The grip faces were rubberized, and thelonger dimension of the grip was perpendicular to the direction of pull.The grip pressure was pneumatically maintained at a pressure of 40pounds per square inch. The tensile test was run using a gauge length of18.0 millimeters and a break sensitivity of 40%. Five samples weretested by applying the test load along the machine-direction and fivesamples were tested by applying the test load along the cross direction.During the test, samples were stretched at a crosshead speed of abut 127millimeters per minute until breakage occurred. The modulus, peakstress, and elongation were measured in the machine direction (“MD”) andcross-machine directions (“CD”).

EXAMPLE 1

A variety of lightly fragranced starch-based biodegradable films werecreated. Thermoplastic starch (“TPS”) was created by dry blending 70%native corn starch from Cargill with 30% sorbitol fromArcher-Daniel-Midland Co., Decatur, Ill. and 2% P40S surfactant (KaoCo., Japan). Thirty-percent Elvanol™ 51-05 polyvinyl alcohol from DuPontwas then added to the Corn TPS to create an overall 70/30 Corn TPS/PVOHblend. This 70/30 blend was fed into the extruder throat via a K-Tronpowder feeder. Firmenich 179132 Fresh Linen was added to the extruder atzone 4 and incorporated into the thermoplastic melt. The resultingpolymer strands were cooled and pelletized before film casting. Table 1below describes the extrusion conditions during the thermoplasticstarch-fragrance addition converting process.

TABLE 1 Extrusion Conditions Powder Extruder Conditions (° C.) ScrewFeed Liquid Z1 = throat; Z4 = liquid injection; Z10 = strand die SpeedTorque Rate Injection Rate Composition Zone 1 2 3 4 5 6 7 8 9 10 (rpm)(%) (lbs/hr) (g/minute) 70/30 Corn TPS/PVA + 0.6% 90 120 150 160 160 150140 130 125 120 150 75 3.5 0.15 Fragrance (Firmenich 179132) 70/30 CornTPS/PVA + 2% 90 120 150 160 160 150 140 130 125 120 150 50 3.5 0.51Fragrance (Firmenich 179132) Corn TPS consists of 70% Native Corn Starchfrom Cargill, 30% Sorbitol and 2% P40S Surfactant (2% of corn starchweight). Corn TPS was dry blended with Elvanol 51-05 PVA and placed inthe powder feeder for thermoplastic converting.

The fragranced Corn TPS/PVOH resin was then dry blended with ECOFLEX® FBX 7011 (BASF) before blown film casting. Three blends were created: 1)56/24/20 Corn TPS/PVOH/ECOFLEX® (majority TPS blend), 2) 49/21/30 CornTPS/PVOH/ECOFLEX®, and 3) 15/6/79 Corn TPS/PVOH/ECOFLEX® (majorityECOFLEX® blend). The blown film processing conditions are shown below inTable 2, while the film tensile property results are shown in Table 3.

TABLE 2 Blown Film Processing Conditions Melt Extruder Conditions (° C.)Temp. Composition Zone 1 2 3 4 5 (° C.) 56/24/20 Corn TPS/PVOH/Ecoflex(0.6% Fresh 160 170 175 180 180 184 Linen Firmenich 179132) 49/21/30Corn TPS/PVOH/Ecoflex (2% Fresh 160 170 175 180 180 184 Linen Firmenich179132) 15/6/79 Corn TPS/PVOH/Ecoflex (2% Fresh Linen 160 170 175 180180 184 Firmenich 179132)

TABLE 3 Film Tensile Properties Sample ID MD CD MD CD MD CD MD CD MD CD56/24/20 Corn TPS/PVOH/Ecoflex (0.6% Mean 1.0 1.1 757 788 13 12 13 9 1.40.8 Fresh Linen Firmenich 179132) 15/6/79 Corn TPS with PVOH/Ecoflex (2%1.3 1.0 527 425 13 12 27 206 28 19 Fresh Linen Firmenich 179132)

As indicated, films made with a majority of Ecoflex® had better filmproperties than those with a majority of Corn TPS. Both films had thecharacteristic Fresh Linen scent, although the scent was much strongerin the film that contained 2% fragrance.

While the invention has been described in detail with respect to thespecific embodiments thereof, it will be appreciated that those skilledin the art, upon attaining an understanding of the foregoing, mayreadily conceive of alterations to, variations of, and equivalents tothese embodiments. Accordingly, the scope of the present inventionshould be assessed as that of the appended claims and any equivalentsthereto.

What is claimed is:
 1. A method for forming a fragranced biodegradablefilm, the method comprising: supplying at least one thermoplastic starchto an extruder and injecting at least one liquid fragrance into theextruder to form a fragranced thermoplastic starch, wherein the liquidfragrance has a boiling point at atmospheric pressure of from about 125°C. to about 350° C., wherein injection of the liquid fragrance isaccomplished without pre-compounding the fragrance, and wherein thethermoplastic starch includes a biodegradable starch polymer plasticizedwith a polyhydric alcohol; blending the fragranced thermoplastic starchwith at least one biodegradable aliphatic-aromatic copolyester to form ablend and casting or blowing the blend onto a surface to form abiodegradable film.
 2. The method of claim 1, wherein the fragrance hasa boiling point at atmospheric pressure of from about 175° C. to about250° C.
 3. The method of claim 1, wherein fragrances constitute fromabout 0.1 wt. % to about 15 wt. % of the film.
 4. The method of claim 1,wherein fragrances constitute from about 1 wt. % to about 5 wt. % of thefilm.
 5. The method of claim 1, wherein the weight ratio ofbiodegradable polymers to fragrances in the film is from about 20 toabout
 80. 6. The method of claim 1, wherein biodegradable polymersconstitute from about 40 wt. % to about 99.9 wt. % of the film.
 7. Themethod of claim 1, wherein biodegradable polymers constitute from about60 wt. % to about 99 wt. % of the film.
 8. The method of claim 1,wherein the blend is extruded at a temperature of from about 75° C. toabout 350° C.
 9. The method of claim 1, wherein the liquid fragrance isinjected into a melt section of the extruder.
 10. The method of claim 1,wherein the thermoplastic starch is supplied to a hopper of theextruder.
 11. The method of claim 1, wherein the biodegradable starchpolymer is a starch ether, starch ester, or a combination thereof. 12.The method of claim 1, further comprising supplying a water-solublepolymer to the extruder.
 13. The method of claim 12, wherein thewater-soluble polymer is a vinyl alcohol homopolymer, vinyl alcoholcopolymer, or a combination thereof.
 14. The method of claim 1, furthercomprising supplying the blend to a second extruder and then casting orblowing the blend onto a surface to form the biodegradable film.
 15. Themethod of claim 1, further comprising orienting the film in at least themachine direction.
 16. The method of claim 1, wherein the film has athickness of from about 1 to about 100 micrometers.
 17. The method ofclaim 1, wherein the polyhydric alcohol is a sugar alcohol.
 18. Themethod of claim 1, wherein polyhydric alcohols constitute from aboutfrom about 1 wt. % to about 40 wt. % of the film.
 19. The method ofclaim 1, wherein the biodegradable aliphatic-aromatic copolyester hasthe following general structure:

wherein, m is an integer from 2 to 10; n is an integer from 0 to 18; pis an integer from 2 to 10; x is an integer greater than 1; and y is aninteger greater than
 1. 20. The method of claim 19, wherein thebiodegradable aliphatic-aromatic copolyester is polybutylene adipateterephthalate.
 21. The method of claim 1, wherein the film comprisesfrom 21 wt. % to 80 wt. % of the fragranced thermoplastic starch andfrom 20 wt. % to 79 wt. % of the biodegradable aliphatic-aromaticcopolyester.